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| Author(s): |
Micássio Fernandes de Andrade
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Ribeirão Preto. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Medicina de Ribeirão Preto (PCARP/BC) |
| Defense date: | 2016-09-29 |
| Examining board members: |
Yara Maria Lucisano Valim;
Fabiani Gai Frantz;
João Alexandre Trés Pancoto;
Karina Alves de Toledo
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| Advisor: | Yara Maria Lucisano Valim |
| Abstract | |
Neutrophils are the most abundant circulating leukocytes. Although neutrophils are important to fight against infections, the massive recruitment and consequent activation of these cells result in the release of inflammatory mediators that are associated with worsening of the clinical condition in many diseases. In this sense, the search for new therapeutic compounds that minimize tissue damage caused by neutrophil infiltration has been intensified in the past few years. Previous studies have demonstrated that 3-phenylcoumarins, a class of plantderived natural compounds, are promising modulators of neutrophil oxidative metabolism. To continue these investigations, we selected the 3-phenylcoumarin derivative 6,7-dihydroxy-3- [3?,4?-methylenedioxyphenyl]-coumarin (C13), bearing the 6,7-dihydroxyl and the 3?,4?- methylenedioxyl groups, to further assess its effects on the other effector functions of neutrophils, as well as on in an animal model of articular inflammation. We examined the in vitro modulator effect of C13 on the human neutrophil chemotaxis, production of ROS and interaction with active site of myeloperoxidase (MPO), phagocytosis of immune complexes (IC), degranulation, killing of Candida albicans, calcium mobilization and influx, cytoskeleton polymerization, and the formation and release of NETs. C13 inhibited, in a concentration-dependent manner, the neutrophil ROS generation elicited via IgG (Fc?R) and/ or complement (CR) receptors using different types of IC and it interacted with active site of MPO. At concentrations near to that required to suppress the ROS production by 50% (~ 2µmol/L), C13 did not modulate the other neutrophil effector functions assessed. However, at the highest concentration tested (20 µmol/L), C13 inhibited nearly: 30% of the cell ability to migrate towards n-formyl-methionyl-leucyl-phenylalanine (fMLP) and leukotriene B4; 70% of CR-mediated phagocytosis of IC; 40% and 80% of cell degranulation triggered by fMLP and immobilized IC, respectively; and 50% of the NETs formation and release process. Such C13 concentration also interfered in the actin cytoskeleton polymerization, but it did not suppress the neutrophil: chemotaxis towards interleukin (IL) 8; capacity to phagocytose IC elicited via Fc?R and Fc?R+CR; and killing of C. albicans. In the second part of this study, we examined whether C13 was toxic towards neutrophils maintained in culture for 6 and 12 h. At the time points assessed, this compound did not change the viability of neutrophils. Finally, we incorporated C13 into liposomes and examined its biological activity in Wistar rats of zymosan-induced articular inflammation. Treatment of animals with liposomal C13 reduced edema formation, and leukocyte and neutrophil infiltration in the inflamed synovia, but it did not change the synovial concentration of the inflammatory cytokines tumor necrosis factor ?, IL-1?, and IL-6. Therefore, the 3-phenylcoumarin derivative C13 can be a prototype for the development of novel therapeutic agents to be used in the treatment of diseases where neutrophils have intense participation. (AU) | |
| FAPESP's process: | 12/23541-4 - In vitro evaluation of antioxidant and anti-inflammatory derivatives 3-phenylcoumarins in human neutrophils stimulated and in animal models of arthritis. |
| Grantee: | Micássio Fernandes de Andrade |
| Support Opportunities: | Scholarships in Brazil - Doctorate |